Process of treating pickled or tanned skins or hides.



UNITED, STATES Patented August 23, 1904.

PATENT OFFICE.

OTTO P. AMEND, OF NEW YORK, N. Y.

PROCESS OF TREATING PICKLED OR TANNED SKINS OR HIDES.

. SPECIFICATION forming part of Letters Patent No. 768,259, dated August 23, 1904.

Application filed November 6, 1903. Serial No. 180,030. (No specimens.)

To all whom it may concern:

' Be it known that I, OTTO P. AMEND, acitizen of the United States, residing in New York city, in the county of New York and State of New York, have invented a new and useful Improvement in Processes of Treating Pickled or Tanned Skins or Hides, of which the following is a specification.

The object of my invention is to reduce the contraction in pickled and tanned skins, which is due to the astringent effect of the acids contained in such skins, and to produce a slight oxidizing effect upon them, and such object is effected 'by my method of neutralizing the acids contained-in such skins.

I accomplish the object sought by immersing the skins in a slightly alkaline or neutral solution of a nitrite of an alkali or of an alkaline earth.

A suitable method of practicing my invention, for instance, is to prepare a solution consisting of ten ounces of nitrite of soda (NaNOz) in, say, seventy gallons of water, so as to make a slightly alkaline or neutral solution. This solution will oxidize and deacidify one doxen pickled Australian sheep-skin's. By

pickled skins I mean skins which have beensubjected to the action of a pickle, but which have not yet been tanned. Various pickles are employed for this purpose in which either sulfuric, hydrochloric, lactic, or acetic acids are used in conjunction with common salt, sodium chlorid, (NaOl;) but'the usual pickle consists of sulfuric acid and sodium chlorid. My

invention is effective with skins pickled in all of these. The quantity of the solution should be regulated, of course, according to the number of skins to be treated. For mineral-tanned skins which contain either sulfuric orhydrochloric acidin the caseof the two-bath chrome process they contain sulfuric acid, hyposulfurous acid, (H2802) and thiosulfuric acid, (II2S20s)OIl the other hand, I prepare a solution, for-instance, of five ounces of nitrite of soda (NaNOz) in seventy gallons of water. This solution is also slightly alkaline or neutral and will deacidify and oxidize one dozen of tanned calf-skins. Upon all these acids at ordinary temperatures the action of the sodium nitrite (NELNOz) is similar, and it also exerts an oxidizing effect on any free sulfur that is present. The quantity of the solution to be used is regulated by the number of tanned skins to betreated.

By the method above described I gain a much larger surface of skin than if my solution were not used, and I also secure an improved quality of the product in that the skins have a much smoother surface and are much more porous and softer. In the treatment of the pickled skins by my solution I find that the skins can be more readily subsequently tanned, owing to their greater receptivity of the tanning liquor.

Of course an excess of the nitrite of soda will not be injurious because it remains in the solution, and, again, somewhat smaller proportions of nitrate of soda than those s pecified may be used with benefit; but I prefer the strength of the solution above stated. In all cases the solution must be either neutral or slightly alkaline.

- Having thus described my invention, what I claim is 1. The process of deacidifying and oxidizing pickled skins and leather which consists in treating them in a neutral or slightly alkaline solutionofa nitrite of an alkali or of an alkaline earth, substantially as described.

2. The process of deacidifying and oxidizing pickled skins and leather which consists in treating them in a neutral or slightly alkaline solution of nitrite of soda, NaNOz, substantially as described.

OTTO P. AMEND.

Witnesses:

FRANCIS WHITE PROSOHER, J. E. HINDON HYDE. 

